package com.asiainfo.web.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.security.access.SecurityMetadataSource;
import org.springframework.security.access.intercept.AbstractSecurityInterceptor;
import org.springframework.security.access.intercept.InterceptorStatusToken;
import org.springframework.security.web.FilterInvocation;
import org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource;

public class MySecurityFilter extends AbstractSecurityInterceptor implements Filter{

	// 与applicationContext-security.xml里的myFilter的属性securityMetadataSource对应，
	// 其他的两个组件，已经在AbstractSecurityInterceptor定义
	private FilterInvocationSecurityMetadataSource securityMetadataSource;

	public FilterInvocationSecurityMetadataSource getSecurityMetadataSource(){
		return securityMetadataSource;
	}

	public void setSecurityMetadataSource(FilterInvocationSecurityMetadataSource securityMetadataSource){
		this.securityMetadataSource=securityMetadataSource;
	}

	@Override
	public void destroy(){}

	@Override
	public void doFilter(ServletRequest request,ServletResponse response,FilterChain filterChain) throws IOException, ServletException{
		FilterInvocation fi=new FilterInvocation(request,response,filterChain);
		invoke(fi);
	}

	private void invoke(FilterInvocation fi) throws IOException, ServletException{
		// object为FilterInvocation对象
		// super.beforeInvocation(fi);源码
		// 1.获取请求资源的权限
		// 执行Collection<ConfigAttribute> attributes = SecurityMetadataSource.getAttributes(object);
		// 2.是否拥有权限
		// this.accessDecisionManager.decide(authenticated, object, attributes);
		InterceptorStatusToken token=super.beforeInvocation(fi);
		try{
			fi.getChain().doFilter(fi.getRequest(),fi.getResponse());
		}finally{
			super.afterInvocation(token,null);
		}
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException{}

	@Override
	public Class<?> getSecureObjectClass(){
		// 下面的MyAccessDecisionManager的supports方面必须放回true,否则会提醒类型错误
		return FilterInvocation.class;
	}

	@Override
	public SecurityMetadataSource obtainSecurityMetadataSource(){
		return securityMetadataSource;
	}
}
